The present invention is for a gasket which provides a seal between a base of a toilet bowl and a closet flange, and more particularly for a gasket which is simple in structure and accommodates substantial variation in the gap between the base of the toilet bowl and the closet flange.
A seal is used between a toilet base of a toilet bowl and a closet flange, which in turn mounts on a floor. When the toilet bowl is installed, the toilet base rests on the floor, and the closet flange is positioned beneath the toilet base. The toilet bowl usually has a horn attached to the toilet base and, when the toilet is installed, the horn extends into the closet flange and directs waste and water into the closet flange when the toilet is flushed. The closet flange in turn opens into a drainpipe which connects to a sewer line that carries the waste-containing water away from the toilet. The seal prevents water from seeping through the gap between the toilet horn and the closet flange when the toilet is flushed and the closet flange is filled with waste water, and also blocks the escape of sewer gases from the drain pipe when the closet flange is not filled. The seal should also preferably prevent water seepage from occurring not only when the toilet is flushed, but also when the closet flange is subject to back pressure from the drainpipe. The elimination of sewer gases and overflow of water from the closet flange improves sanitation and prevents water damage to the surrounding floor.
Classically, the seal has been provided by a ring of soft deformable wax. The wax seal is designed to have an opening sufficient to accept the horn on the base of a conventional toilet. The wax seal is also chosen to be pliable enough that, when compressed between the toilet base and the closet flange when the toilet base is secured with respect to the closet flange by mounting bolts, the compression of the wax seal deforms the ring to the contour of the toilet base and the closet flange, creating a seal therebetween when the base rests on the floor. However, these seals may be subject to loads during assembly which can cause deformations that distort the ring and can result in the ring failing to seal the toilet base with respect to the closet flange when the toilet base rests on the floor. For example, deformation caused when setting the toilet base onto the floor can cause damage to the ring by distorting its profile, thereby resulting in unsealed regions of the toilet base with respect to the closet flange. The properties of these wax seals are also strongly temperature dependant, and can result in thermal creep over time which can eventually result in leakage. The problems associated with thermal creep are particularly troublesome in buildings with radiant heating installed into the floor, since the resulting heat in the floor can accelerate creep and, in some cases, could result in at least partial melting of the seal. The problem of melting when subjected to high temperatures can also create problems when wax seals are stored in an environment where the temperature is elevated. An additional problem with wax seals is their lack of elastic deformation, which limits the ability of the seal to conform to irregularities in the contour of the toilet bowl base, which can contribute to leakage. Furthermore, if the toilet is rocked or shifts over time, the seal may pull away from either the toilet base, the horn, or the closet flange.
Many attempts to overcome the shortcomings of the wax seal have been tried. Many other materials, including rubber gaskets and foam rings have been tried as substitutes for the wax seal, but none have met with success. The rubber materials are reported to tend to pull away from the surfaces over time. Foam rings provide elastic behavior and are better able to conform to any irregularities, but foam materials are permeable, allowing the seal to be penetrated in time, and are highly subject to deterioration over time. One attempt to overcome these problems has been to fill the cells of the foam with wax, as taught in U.S. Pat. No. 3,400,411; however, this solution has proven to be less than satisfactory. The wax-filled foam is still liable to set once in place, resulting in leakage if the toilet is rocked or shifted. Even if the foam retains sufficient resiliency to compensate for shifting, the wax in the cells will tend to remain in its deformed state, and may create paths for water to permeate through the seal.
Various other devices have attempted to overcome the problem of providing a seal. Such devices are taught, for example, in U.S. Pat. Nos. 2,750,216; 2,976,543; 3,224,014; 3,349,412; 3,400,411; 3,821,820; 4,423,526; 4,482,161; and 5,185,890.
U.S. Pat. No. 2,750,216 teaches one attempt to overcome the deficiencies of wax and sponge rubber seals by employing a ring gasket of wax or sponge rubber with a tapered sleeve or ferrule extending downwardly therefrom. The upper end of the ferrule has a flange which engages an annular slot in the ring, while the lower end of the ferrule extends into the drain and is sized to be spaced away from the sidewall of the drain to prevent leakage through capillary action. U.S. Pat. Nos. 2,976,543; 3,224,014; 3,349,412; 3,400,411; and 3,821,820 teach similar seals which employ ferrules.
Another attempt to overcome the problems due to lack of resiliency in wax seals is taught in U.S. Pat. Nos. 4,423,526 and 4,482,161, which teach reusable gaskets formed of xe2x80x9cmemory materialxe2x80x9d, such as rubberlike PVC, which are compressed between the toilet horn and the closet flange. The gaskets of the ""526 patent have a disk which extends over the entire surface of the closet flange, having holes for receiving the toilet bolts. The gasket of the ""161 patent, which is a CIP of the ""526 patent, has a sealing ring portion for sealing between the toilet horn and the closet flange, and a surrounding sheet-like web portion which covers the closet flange and has concentric ridges for sealing between the toilet base and the closet flange. The ""161 patent also teaches a preferred hardness of the xe2x80x9cmemory materialxe2x80x9d of durometer 60 (Shore Axc2x15). While these patents teach a reusable seal, neither provides for a universal seal which can be used where the gap between the toilet horn and the closet flange differs significantly from one installation to another. Furthermore, since the contact area is large, the pressure on the seal will be small and effectiveness of the seal is due in part to the large area of the seal. However, when the flange surface is tilted with respect to the floor, this tilt reduces the effective contact surface and thus the sealing area. In which case, seepage can result if the sewer line backs up, creating a head of waste water above the seal.
U.S. Pat. No. 5,185,890 is designed to overcome the problem of accommodating variation in height between the toilet horn and the closet flange which may occur in various installation situations. The invention of the ""890 patent accommodates variation in height by employing a semi-rigid funnel which is adhered to the toilet bowl to form an extension of the horn, and a sealing ring of neoprene-like material configured to be compressed between the funnel and the closet flange. The sealing ring either extends to substantially cover the closet flange, having bolt holes, or may be adhered to the closet flange. While this seal may overcome the problem of variation in the separation between the toilet horn and the closet flange in various installations, it requires a more complex structure and creates a protrusion which extends below the base of the toilet, with the result that the toilet cannot be rested on its base unless there is a hole for receiving the funnel.
Thus, while may seals have been developed to overcome the shortcomings of the wax seal, they have at best been only partly successful, and for this reason have not met with great commercial success. Despite its known deficiencies, the wax seal remains the standard.
Thus, there is a need for a toilet bowl gasket which overcomes the deficiencies set forth above while maintaining a simplified structure and ease of use.
The present invention is a gasket for placement between a toilet base, having a horn attached thereto, and a closet flange, having a central opening that is bounded by a central opening sidewall which intersects and terminates at a substantially planar flange upper surface. In practice, the closet flange may be set with the flange upper surface at substantially different heights relative to the floor on which the toilet base is to rest. Typically, the closet flange has a central plastic portion, containing the central opening and at least a portion of the flange upper surface, and a surrounding metal portion which mounts to the floor or an underlying subfloor. The toilet base in turn is held in position on the floor with mounting bolts which couple the closet flange to the toilet base. The mounting bolts are spaced apart by a bolt distance Db.
The gasket of the present invention has a ring having a ring diameter Dr which is less than the bolt distance Db. The ring is fabricated from a water impermeable elastomer having a hardness of less than about durometer 50 (Shorexc2x15). An elastomer is chosen which is resilient to provide a material with a memory so that, if it is subjected to a variation in its state of compression, it will expand and contract in accordance with the pressure to provide a seal at all times. The elastomer may be either a fully dense material, defined herein as a material which is substantially free of distributed cavities or voids, or a closed cell foam, since either can provide a water impermeable elastomer. The ring has a substantially planar ring upper surface which is spaced apart from a substantially planar ring lower ledge by a separation distance S. The term xe2x80x9csubstantially planarxe2x80x9d as used herein is intended to include planar surfaces, gently curving surfaces, or undulating surfaces where the height differences are sufficiently small that, when the surfaces are in service, there are no interconnected paths that transverse these surfaces. The separation distance S is selected to be sufficiently large that the material between the ring upper surface and the ring lower ledge is compressed when the toilet is installed on the closet flange with the ring interposed therebetween.
The compressive load applied when the toilet is mounted to the closet flange should compress the gasket material of the ring sufficiently to create a seal between the toilet base and the closet flange when the toilet base rests on the floor. Since the gasket is resilient, it can accommodate irregularities in the surfaces on which it resides and expand to forcibly conform to these irregularities. The resilient character of the material also allows the ring to accommodate variations in the height of the flange upper surface with respect to the floor. It is preferred that the separation distance S be at least about xc2xd inch (13 mm) to assure compression of the ring when the toilet base is drawn down to the floor in situations where the closet flange is mounted on a subfloor. The combination of having S of at least about xc2xd inch (13 mm) and the ring diameter Dr restricted to less than the bolt separation Db enhances the ability of the gasket to accommodate for tilt between the floor and the flange upper surface.
The ring is further bounded by a ring inner surface and a ring outer surface, which is spaced apart from the inner surface. The ring inner surface is configured to surround a portion of the horn of the toilet base when the horn is placed within the ring, and preferably conforms to the contour of the horn. The ring outer surface defines the ring diameter Dr.
The ring may be formed as a cylinder having a substantially rectangular cross section and a thickness T. In such cases, when the thickness T of the nearly cylindrical ring shape is maintained at less than about xc2xc inch (6 mm) and the ring is fabricated from materials having a hardness of less than about durometer 50 (Shore Axc2x15), it is preferred that the separation distance S not be greater than about 0.9 inch (23 mm). This limit of the separation distance S avoids having the compressive loads needed to bring the toilet base into contact with the floor so large as to cause a risk of fracturing the ceramic toilet base before the toilet base is drawn down to the floor. At greater thicknesses of about xe2x85x9c inch, the hardness of the ring should be reduced to about durometer 35 (Shore Axc2x15) and the maximum height should be restricted to about 0.8 inch (20 mm).
While essentially cylindrical rings can be employed, it is preferred for the ring outer surface to converge sightly as it approaches the substantially planar ring upper surface, making the cross section of the ring trapezoidal in character. This shape is preferred if the ring is to be injection molded, since it facilitates release of the ring from the mold and allows fully dense materials to be formed. A trapezoidal cross section with a large base is further preferred, since it enhances the buckling strength of the ring. When rings are employed that have a trapezoidal cross section designed to enhance the buckling strength, the ring should have a minimum thickness Tmin at the ring upper surface which is no greater than about 85% of a maximum thickness Tmax which occurs at the ring lower ledge. The ring is preferably configured such that Tmax is at least about xc2xd of the separation distance S, and more preferably that Tmax be about the value of the separation distance S to add to stability of the ring when compressed.
Since rings with trapezoidal cross sections are generally more massive than cylindrical rings, and thus it is again preferred that the maximum separation distance S be limited to at most about 0.8 inches (20 mm) to reduce the compression forces required to seat the toilet with respect to the floor. For rings having a separation distance S near the top of this range, it is preferred for the ring to be fabricated from material having a hardness below a durometer of 35 (Shore Axc2x15) and preferably lower. For a molded multi-part ring, a practical lower limit is a durometer of 25, since softer materials can not be readily withdrawn from the mold in which they are formed without ripping. The ring can be formed with a solid trapezoidal cross section or, as discussed in greater detail below, the ring can have a multi-component structure which forms an overall trapezoidal cross section. While solid trapezoidal rings are effective in providing a seal, they have been found to require expertise in installation to avoid fracturing the toilet base unless compensation can be made for the increased cross section of the ring.
The gasket also has an annular extension which is attached to and protrudes from the ring lower ledge, and which is preferably formed as an integral part of the ring. The annular extension has an extension outer surface extending from the ring lower ledge and configured to be insertable into the central opening of the closet flange such that, when so inserted, the ring lower ledge abuts the flange upper surface. The annular extension preferably has a vertical extent less than the separation distance S of the ring.
An extension inner surface is spaced apart from the extension outer surface and preferably continuously extends the ring inner surface so as to avoid any discontinuity between the two which might collect waste matter. When the annular extension is inserted into the central opening of the closet flange, the ring lower ledge rests against the flange upper surface. Preferably, the extension outer surface is closely matched in size to the central opening of the closet flange, so that the annular extension engages the central opening to maintain the gasket centered thereon during installation of the toilet base. It is preferred for the extension outer surface to be slightly tapered, narrowing as the distance of the surface from the substantially planar ring lower ledge increases, so as to facilitate insertion of the annular extension into the central opening while assuring contact with the central opening sidewall in the vicinity of the flange upper surface. The tapered profile also provides a benefit when the gasket is to be fabricated by molding, since it provides draft to facilitate removing the gasket from the mold. When the gasket is to be molded, the extension inner surface is preferably also tapered, but with a reversed taper to the taper of the outer surface, and is preferably also contoured to be substantially continuous with the ring inner surface of the ring to avoid forming a discontinuity in the surface, as noted above.
Where resistance to water pressure resulting from a back-up of a sewer line creating a head of water above the seal is critical, such as for applications where the toilet is subject to backfilling by a sewer line back-up, a high buckling strength is advantageous to assure a seal is maintained. For such applications is preferred to employ a ring having greater effective buckling strength without an associated increase in the stiffness of the material of the ring which could result in fracture of the toilet base during installation. It is also preferred that ring be capable of providing a greater component of the pressure resulting from compression of the ring to be applied to the horn of the toilet base. Such increased buckling strength can be provided by employing a rigid support sleeve in combination with a thin cylindrical ring, or alternatively by employing a multi-component quasi-trapezoidal ring in the gasket. This quasi-trapezoidal ring has a cross section that is essentially trapezoidal, with a groove extending upward from the substantially planar ring lower ledge.
The multi-component ring structure is the preferred structure, since it is an integrated unit which simplifies installation and because it can accommodate a greater range of deformations than do gaskets employing a rigid support sleeve. Furthermore, for similar hardness of the material from which the rings are fabricated, the multi-component rings provide a greater range of deformation than the equivalent sized solid ring having a trapezoidal cross section.
The multi-component structure has an upper continuous region, an inner diverging leg that forms an inner hoop having an inner surface which forms part of the ring inner surface, and an outer diverging leg that forms an outer hoop having an outer surface which forms part of the ring outer surface. These surfaces form the non-parallel sides of the trapezoidal cross section of the ring. The inner diverging leg and the outer diverging leg of the ring are spatially arranged with the upper continuous region extending downwardly from the substantially planar ring upper surface, having attached thereto the inner diverging leg and the outer diverging leg. The inner diverging leg terminates at an inner leg free end which forms an inner part of the substantially planar ring lower ledge. Similarly, the outer diverging leg terminates in an outer leg free end which forms an outer part of the substantially planar ring lower ledge. The inner diverging leg and the outer diverging leg are separated by a groove having a substantially triangular cross section with a groove depth D and a groove breadth B which separates the inner part and the outer part of the substantially planar ring lower ledge.
It is further preferred that the ratio of the groove depth D be maintained between about 60% and 80% of the separation distance S. The lower limit assures sufficient compressibility of the ring, while the upper limit assures sufficient strength of the multi-part structure. It is also preferred that the groove breadth B be maintained between 30% and 40% of the groove depth D, and that the inner diverging leg have a mean thickness tinner which is greater than the mean thickness touter of the outer diverging leg. Preferably, the mean thickness tinner of the inner diverging leg is 50% to 60% greater than the mean thickness touter of the outer diverging leg. It is also preferred that the outer diverging leg have a thickness touter of at least about {fraction (3/16)} inch (5 mm) and more preferably xc2xc inch (6 mm), so as to provide significant additional support for the substantially planar ring upper surface as well as increased pressure of the ring inner surface against the horn. Both of these enhance the sealing capacity of the ring; however, this is accomplished by a loss in the deformability of the resulting ring when compared to a ring which lacks an outer diverging leg.
It is further preferred for the substantially planar ring upper surface to be provided with a concentric indentation. The concentric indentation provides the upper surface with greater deformability to better conform to the contours of the toilet base and can also be used for locating a bead of caulk or similar sealant to further assure a seal between the ring and the toilet base.